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Background Attack Aftermath Evidence Misinformation Analysis Memorial

Basement Bombs

Theories that Subterranean Bombs Destroyed the Twin Towers

Theories that powerful bombs in the basements of the Twin Towers were partly or wholly responsible for their collapses have enjoyed some circulation. They have been fed by reports of molten steel in the Towers' foundations and dubious interpretations of seismic data.

The presence of high temperatures on the surface of the rubble pile is documented by remote sensing data from September 16 and 23, and the persistence of smoke-generating fires into December. There are also numerous reports of molten metal in portions of the rubble pile as late is mid-October. These features, while they may be evidence for the use of high explosives or thermite, are not evidence that such were used to attack the foundations of the Towers to begin the collapses.

This segment from the Palisades seismic chart shows the onset of the signal for the South Tower collapse, where the vertical lines denote 10-second intervals. The collapse probably starts about four seconds into this segment, indicated by the marked increase in amplitude. That increase is small compared to the much larger amplitudes apparently caused by the rubble crashing onto the ground, starting about twelve seconds later. For a more in-depth look at this topic, see Seismic Records of the Twin Towers' Destruction: Clarifying the Relationship Between Seismic Evidence and Controlled Demolition Theories

Misinterpreting the Seismic Data

Proponents of basement bomb theories have adduced questionable interpretations of seismic data. They have suggested that the largest seismic spikes were generated at the beginnings of the collapse events. This ignores the marked increases in amplitude that start about ten seconds before the large spikes start. The most referenced charts are those recorded at the Lamont-Doherty station in Palisades, NY. These show a large signal lasting about eight seconds followed by a smaller one lasting more than fifteen seconds. The amplitudes of these signals make it easy to miss the signals that start about ten seconds before the large ones. Those smaller signals are still several times greater than the baseline signal seen at the beginning of the charts. Thus, contrary to indicating strong ground-coupled explosions of basement bombs at the collapses outsets, the charts suggest that the large spikes registered the ends of the collapse events, when the rubble reached the ground.


Eyewitness Reports

Theories that basement bombs were causative in the collapses should not be confused with theories that bombs damaged the basements and lobbies of the Towers at around the times of the plane crashes. An article in ChiefEngineer.org contains a detailed account of Stationary Engineer Mike Pecoraro containing descriptions of profound damage in the basement of the North Tower following the plane crash. 1   This report has been combined with observations that windows in the lobby of the North Tower were broken to support the idea of basement bombs were detonated coincident with the plane crashes. However, detailed corroboration of Pecoraro's account has not emerged, either in media reports like the ChiefEngineer.org's or in the detailed oral histories of emergency responders. Furthermore, there are other possible explanations for the damage in the lobby, such as impacts from ricocheting debris from the plane impact, and for damage in the basement, such as explosions of electrical equipment.

The individual whose accounts of explosions in the basements of the World Trade Center have received the most publicity is William Rodriguez, a janitor who helped victims escape from the Twin Towers during the attack. In an interview about his experiences on the morning of 9/11/01, Rodriguez describes hearing an loud explosion in the basement followed a few seconds later by a second explosion that sounded like it came from far above. 2   Rodriguez' account has been used to support basement bombs theories, including the idea that bombs exploded in the basement just before Flight 11 hit the North Tower. However, there are many possible explanations for Rodriguez' recollections, such as secondary explosions triggered by the crash.

Rodriguez, a lauded hero of the 9/11 attack, swears that he saw Mohald Alshehri, an alleged hijacker of Flight 175, in the World Trade Center in June of 2001. 3   Assuming Rodriguez didn't know Alshehri, this would be a remarkable feat of memory: viewing mug shots of the alleged hijackers, Rodriguez recognized one as being a someone he saw some three months earlier among the thousands of strangers he must have seen in the course of his work.

The body of oral histories of emergency responders has dozens of accounts of perceptions of explosions high in the building coinciding with or slightly preceding the onsets of each Tower's destruction. Apparently absent from the accounts are recollections of large explosions low in the Towers at the outsets of these events. That should not be confused with the perception of flashes. Stephen Gregory stated:

I thought that when I looked in the direction of the Trade Center before it came down, before No. 2 came down, that I saw low-level flashes.
I know about the explosion on the upper floors. This was like at eye level. I didn't have to go like this. Because I was looking this way. I'm not going to say it was on the first floor or the second floor, but somewhere in that area I saw to me what appeared to be flashes.

Flashes suggest explosive devices detonating. However, there is no credible photographic, video, or eyewitness evidence supporting the notion that large explosions low in the building preceded the descents of the exploding rubble from around the crash zones down to the ground. Instead, the flashes are consistent with a theory of demolition in which thermobaric devices are detonated in a sequence from the crash zones downward. Since such devices may employ a small charge to disperse the fuel, followed by a secondary explosion to ignite the mixture and produce a large structure-shattering explosion, the flashes seen by Gregory may have been the dispersal charges preceding the main explosions by ten or more seconds.

excavation of North Tower rubble
This photograph from this collection shows a standing fragment of the base of the North Tower's core. This suggests that the core was destroyed from the top down, not by bombs in the basements.

Nuclear Devices

Basement bombs theories are often found in conjunction with the nuclear attack theory. For example, Rick Siegel promotes both ideas in his film 9/11 Eyewitness and in his talks. Although the two theories dovetail with each other, both are blatantly contradicted by the evidence.


Failures of the Theory

Some investigators have suggested that basement bombs by themselves, or in combination with failure scenarios of official theories, brought down the Twin Towers. These suggestions are not tenable in light of the observed features of the collapses. Bombs that destroyed the bases of the Towers' core columns would not cause the Towers to collapse in the rapid top-down manner observed, nor to totally collapse in any fashion. The core structures were surrounded by the floor diaphragms, which were in turn surrounded by load-bearing perimeter columns. The obliteration of a few stories of core columns just above the foundation may have led to the entire core structures, from the basement to the roof, falling several stories before coming to rest on the foundations. That would have damaged most of the floor diaphragms, and may have even caused some kind of perimeter wall failures. However, such damage would have occurred nearly simultaneously from the bottom to the top of each Tower. It would not have looked anything like the observed methodical destruction starting from the crash zones and proceeding down the Towers.

The combination of basement bombs with the dubious truss failure scenario also cannot account for the destruction observed for all of the following reasons:

  • Most of the concrete in the Towers was apparently pulverized to dust the consistency of talcum powder in the air. That required far more energy than floors falling a few feet or even a thousand feet.
  • The mushrooming of the Towers into dust clouds three to five times the diameter of each Tower before the destruction reached the ground cannot be explained by the falling of floors and damage to the core foundations.
  • The dust evolving from each Tower before it reached the ground was already several times the Tower's original volume. Only huge inputs of heat in portions of the building above the ground can account for that.
  • This South Tower collapse video shows most of the block of stories above the impact zone breaking up before it started to fall. The steel columns of the perimeter wall wouldn't simply shatter due to a lack of support from the core and floors.

In addition to all of the above, all theories that basement bombs were instrumental in the destruction of the Towers are directly contradicted by the accounts of members on Ladder Company 6 who survived the destruction of both Towers trapped in the North Tower's B stairway. 4  


1. We Will Not Forget, ChiefEngineer.org, [cached]
2. William Rodriguez 9/11 Interview, Google Video,
3. Janitor tells 9/11 panel of brush with WTC thug, NY Daily News, 6/15/04 [cached]
4. The Miracle of Ladder Company 6, NBC News, 9/28/01 [cached]

page last modified: 2013-03-20